Marvel Two-in-One #51

The cover by George Pérez and Joe Sinnott says it all: the Thing charges forward shouting "It's Clobberin' Time!" flanked by Ms. Marvel, the Beast, Wonder Man, and a gun-toting Nick Fury in a five-hero charge that earns every word of the "Avengers Assemble!" burst above them. Subtitled "A Gathering of Heroes," this May 1979 issue delivers one of the series' most crowd-pleasing lineups, pairing Marvel's rockiest hero with some of the Avengers' heaviest hitters. If you've ever wanted to see Ben Grimm surrounded by that much firepower in a single issue, this is a very satisfying place to look.